Haploid gametes, that are essential for sexual reproduction, are generated fronn diploid precursor cells via meiosis. In females, oocytes undergo 2 major meiosis-specific, cell-cycle transitions wtiose regulation are poorly understood. Thie first transition is meiotic resumption where oocytes exit a prolonged prophase arrest and enter the first meiotic M phase (Ml), and the second is the transition between Ml and Mil where homologous chromosomes separate and no round of DNA synthesis occurs. This project began while the PI (Karen Schindler) was a postdoctoral fellow at the University of Pennsylvania and has facilitated transition to an independent research career. These studies investigating the molecular mechanisms that lead to aneuploidy in female eggs will form the basis of an independent research program in the Department of Genetics at Rutgers, The State University of New Jersey where the PI will assume a tenure-track faculty position in January 2012. The environment at Rutgers for research in reproductive biology and aneuploidy is outstanding, all resources required to complete the studies are available, and the institution is committed to promoting development of new investigators. Thus, the PI will be well-positioned to compete for additional funding and to have a successful independent research career.